LF: 17.52kHz earth mode test

[Roger Lapthorn <rogerlapthorn@gmail.com>]

This morning I did an initial test at 17.52kHz using my 5W QRSS3 TX and earth electrode TX "antenna".  Signals at 1.6km were ~30dB over noise with the 30t loop on the ground but zero copy with the loop oriented towards the home QTH vertically. With a pair of earth electrodes parallel to the road the signal was somewhat weaker than with the horizontal loop.

A test at 3.5km from home showed the signal ~20dB over noise (0.73Hz BW QRSS3) using the 30t loop on the ground and with a 1t loop (about 20m sq) laying in the road (see attached Spectran screenshot). Signals were also copied with the earth electrodes parallel to the road but weaker than on the loop. They were also copied weaker still with the RX earth electrodes strung across the road.

Signals are definitely coming through the ground/utilities with no evidence of any radiated signal and they are every bit as strong (or stronger) than at 8.76 or 1.095kHz.  However, at another test site 4km from home where I usually manage to copy 
8.76kHz QRSS3 reasonably well there was no sign of my 17.52kHz signal 
either with the 30t loop or the earth electrode antenna. No idea why.

Later today I may try the 17.52kHz test at my 6km distant test site with a long duration carrier, although I suspect I may copy it in QRSS3, which I'll try first. I may also try a test using my 80m sq vertical loop as the antenna at the TX end, although I don't expect any great range by pure induction.

73s
Roger G3XBM
-- 
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/

17520_tubney_1t_loop_3500m.jpg
Description: JPEG image